Abstract: Objective The aim of this study was to explore the CT imaging manifestation of congenital choledochal cysts (CCC) in children with different Todani classification.Methods 126 children with CCC admitted to our hospital between January 2013 and June 2020 were selected for the study. All children received plain CT scan and enhanced CT scan after admission, then, underwent surgical operation for CCC. The CT imaging manifestations were summarized and its diagnostic efficacy was estimated when the histopathological examination was done as the gold standard.Results Out of the 126 children with CCC, the postoperative histopathologic diagnosis found Todani Ⅰ in 36 cases, Ⅱ in 10 cases, Ⅲ in 11, Ⅳ in 34, and Ⅴ in 35 cases; the preoperative CT feature in Todani Ⅰ was different size of cysts or a cystic masses between the hilar area of liver and pancreatic head; in Todani Ⅱ, the CT showed the cystic low density and smooth edges of lateral wall of common bile duct, with gallbladder and intrahepatic bile duct normal; in Todani Ⅲ, the CT showed the lower part of common bile duct cystic dilatation, with gallbladder and gallbladder tube normal; in Todani Ⅳ, the CT demonstrated the low density of bile duct inside and outside the liver cystic dilatation in multiple sizes; in Todani Ⅴ, the CT found the cyst in the liver, almost watery density; the CT preoperatively diagnosed children with CCC Todani typeⅠ with the sensitivity (Se) of 83.3%, the specificity (Sp) of 93.3%, the accuracy (AC) of 90.5%, the positive predictive value (PPV) of 83.3%, and the negative predictive value (NPV) of 93.3%; in the diagnosis of Todani type Ⅱ, the Se, Sp, Ac, PPV and NPV were 50.0%, 95.7%, 92.1%, 50.0% and 95.7%; in the diagnosis of Todani type Ⅲ, the Se, Sp, Ac, PPV and NPV were 54.5%, 93.9%, 90.5%, 46.2% and 95.6%; in the diagnosis of Todani type Ⅳ, the Se, Sp, Ac, PPV and NPV were 85.3%, 91.3%, 89.7%, 78.4% and 94.3%; in the diagnosis of Todani type Ⅴ, the Se, Sp, Ac, PPV and NPV were 80.0%, 97.8%, 92.9%, 93.3% and 92.7%.Conclusion The CT manifestations of CCC in children with different Todani types are characteristic, which might help the preoperative diagnosis and dealing with it appropriately.

Key words: Congenital choledochal cyst, CT scan, Todani type, Children